1. Technical Field
The present invention relates to an inline axial flow fan having a plurality of axial flow fans arranged in an inline manner along a rotational shaft direction of a rotational driving apparatus.
2. Description of Related Arts
An axial flow fan includes an impeller having a plurality of rotor blades installed in a rotational shaft of a rotational driving apparatus, a cylindrical casing that forms an axial flow along with the impeller, and a plurality of stator blades installed in an inner circumferential portion of the casing.
Typically, an air-blowing property of the axial flow fan is characterized in a large air volume and a small static pressure. In order to improve the air-blowing property of the axial flow fan, various inline axial flow fans have been proposed, in which a plurality of axial flow fans is arranged in an inline manner along a rotational shaft direction of a rotational driving apparatus.
As a technique regarding the inline axial flow fan, there has been proposed an axial flow fan having a first axial flow fan, a first flow control grid, a second axial flow fan, and a second flow control grid sequentially arranged in an inline manner from an upstream side along an airflow direction (for example, refer to Japanese Patent Application Laid-Open Publication No. 2012-026291). In the axial flow fan disclosed in Japanese Patent Application Laid-Open Publication No. 2012-026291, the first flow control grid has a stator blade having an elbow shape bent with respect to a rotational direction of the first axial flow fan, and the second flow control grid has a stator blade having a trailing edge shape extending in parallel with the airflow direction.
However, the axial flow fan discussed in Japanese Patent Application Laid-Open Publication No. 2012-026291, the first flow control grid has a stator blade having an elbow shape bent with respect to the rotational direction of the first axial flow fan. In addition, the second flow control grid has a stator blade having a trailing edge shape extending in parallel with the airflow direction.
Therefore, discontinuity of the stator blade shape is generated in a border between the stator blade of the first axial flow fan and the stator blade of the first flow control grid and a border between the stator blade of the second axial flow fan and the stator blade of the second flow control grid. If the stator blade shape is discontinuous, a turbulent flow may be generated in the discontinuous portion, and this may adversely influence reduction of a power consumption and a load noise.